code: def test_explode_string() -> None:
      df = pl.Series("a", ["Hello", "World"])
      result = (
          df.to_frame().select(pl.col("a").str.explode()).to_series()
      )
  
      expected = pl.Series(
          "a", ["H", "e", "l", "l", "o", "W", "o", "r", "l", "d"]
      )
      assert_series_equal(result, expected)
  
imports: from __future__ import annotations
  import pyarrow
  import pytest
  import polars
  import polars.selectors
  from polars.testing import assert_frame_equal, assert_series_equal
label_desc: Use image node_id 1 for calling a global function with example usage: test_explode_string() without return types